A pump/air separator apparatus for use in dispensing gasoline includes an air separator of the cyclone type in which air and a low percentage of gasoline are removed from the pressurized gasoline by the air separator, with the air being vented to the atmosphere and the gasoline being returned to the suction side of the pump. Simultaneously pure gasoline is delivered from the air separator through an outlet valve to a meter and then to the nozzle dispenser, and any excess of such pure gasoline is by-passed back to the suction side of the pump.

3. A compact pump/air separator as in claim 1, wherein the opening between the first and third cavities is tapered and wherein a pin, positioned by a float valve is provided in said third cavity for controllably throttling the flow of gasoline from said third cavity to said first cavity.

4. Apparatus as in claim 1 wherein the pressurized fluid flowing through the air separator of the tangential entry cyclone type assumes a helix angle between 10° and 30° .

5. A compact pump/air separator for pressurizing gasoline flow and separating air and vapor therefrom comprising:

7. A compact pump/air separator as in claim 5, wherein said air separator includes a scavenging tube located at the core of the separator wherein the air and vapor and small percentage of gasoline are collected, said scavenging tube being in communication with the means for separating the air and vapor from the small percentage of gasoline.

8. A compact pump/air separator as in claim 5 wherein said second valve means includes a float valve provided in said means for separating the air and vapor from the small percentage of gasoline to control the flow of gasoline to the inlet side of said pump means.

9. A compact pump/air separator as in claim 5 wherein the pressurized fluid flowing through the air separator of the tangential entry cyclone type assumes a helix angle between 10° and 30°.

Description:

BACKGROUND OF THE INVENTION

The present invention relates to a gasoline dispensing pump provided with an air separator, the latter being capable of separating air and vapor from the gasoline received from the storage tank.

A specific application of the present device is in a gasoline dispensing installation where a pump located above ground level delivers gasoline from an underground storage tank through a gasoline meter connected to a computer and register, and thence through a flexible hose and a dispensing nozzle at the delivery end of that hose, where the gasoline flow is controlled by operation of a valve in the nozzle. Because the gasoline must be lifted from the underground storage tank, the suction side of the pump is necessarily below atmospheric pressure. Thus, if any leaks exist in the piping between the storage tank and the pumping apparatus, air would be introduced into the system. Since the meter used is a positive displacement type which will measure both air and liquid, in order to satisfy the various governmental regulations governing commercial gasoline dispensing equipment, it is necessary to separate the air before measuring the volume of delivery.

In the usual gasoline dispensing installation, the pumping apparatus and the separator apparatus are separate and distinct units interconnected by a suitable conduit. The separator allows the bubbles in the pressurized gasoline leaving the pump to rise in a liquid surface under the action of gravity, where the air is separated from the liquid. This is not entirely satisfactory since small bubbles take a very long time to rise, and furthermore, an air separator of this type requires a very large chamber. The latter requirement gives rise to a critical problem in light of the limited space available in the dispensing stand or pedestal for housing the necessary equipment for pumping and dispensing gasoline. Many other factors must also be taken into consideration in a gasoline dispensing installation, one factor being the rigid requirement for accuracy of metering and delivering of gasoline as set forth in various government regulations. Another factor to be considered in a gasoline dispensing installation is the problem caused by the wide and infinite variation in rates of delivery flow of gasoline, and the frequent and abrupt changes in flow rates. This irregularity in flow rates is caused by operation of the control valve at the delivery nozzle, and gives rise to a problem of effectively eliminating the air from the pressurized gasoline leaving the pump in view of the effects of pressure on the solubility of air in gasoline.

As mentioned above, one prior art approach (as shown in U.S. Pat. No. 2,351,331) to achieving the separation of air from gasoline received from a storage tank is to provide a rather large air separator (element 3 of said U.S. Pat. No. 2,351,331) disposed downstream of and completely separate from the main gasoline pump. Other systems have employed arrangements of check valves which are operated in response to a signal developed during operation of the pump. The check valve arrangement takes a signal from the operation of the pump which detects changes in the air-to-liquid ratio of the fluid being forced into the flow lines, and the signal produced by such device operates various valve means to prevent the metering of all but a small quantity of fluid unless the signal indicates a normal fluid flow condition. This type of air separation system is extremely complex, thereby resulting in high cost and questionable reliability.

SUMMARY OF THE INVENTION

The pump/air separator of the subject invention comprises a housing having at least three cavities. A pump is mounted in one cavity and its suction side is connected to the underground gas storage tank. Pressurized gasoline from the pump is directed to an air separator where a scavenged flow of gasoline and air bubbles is then passed through the third cavity, while pure gasoline is passed to the second cavity. The pure gasoline is either delivered to the metering device for subsequent delivery to the flexible hose and dispensing nozzle, or by-passed back to the suction side of the pump. The scavenged flow collects in the third cavity, with the air separating from the gasoline and being discharged through a vent in the housing. The gasoline in the third cavity is controllably returned to the suction side of the pump.

Accordingly, it is a primary object of this invention to provide a compact apparatus embodying means for pumping pressurized gasoline and means for separating air and vapor from the pressurized gasoline prior to dispensing. Thus, the compact apparatus of the subject invention satisfies the critical space requirements for gasoline dispensing apparatus. It is a further object of this invention to provide an improved air separation mechanism which will eliminate substantially all of the air in the pressurized gasoline regardless of the varying conditions under which the associated pump operates. It is a further object of the invention to provide compact pump/air separator which will satisfy all applicable governmental requirements, including the complete elimination of all air that can possibly be eliminated regardless of installation conditions and regardless of the particular conditions under which the operator operates the installation, and especially to accomplish these objects in a manner which will satisfy the rigid requirements for accuracy of metering and delivering of gasoline.

The device of this invention accomplishes these results by using a "cyclone" type of device in a manner which is the inverse of the normal use of such a device. Thus in Mark's Handbook (6th Ed.) at page 759 reference is made to inertia separators of the cyclone type used in the field of industrial dust collectors. In such applications such a device separates heavier particles of dust, etc., from the lighter gases by inertia separation. In the device of this invention the lighter fluid components of a fluid stream are separated from the heavier. Thus air or vapor entrained in gasoline is separated before the gasoline is delivered to the metering device and hence to the outlet nozzle. Similarly the device of this invention may be used to separate particulate matter of a lighter density than the desired fluid or to separate the lighter of two different density and immiscible liquids, i.e., to separate oil from water. While the description below is related only to the specific preferred embodiment of a gasoline pump/air separator, it should be understood that any device which embodies the means described to accomplish the functions performed is within the scope of this invention.

Further objects and advantages of the invention will appear from the following description, taken in conjunction with the following drawings.

FIG. 2 illustrates a partial cross-sectional view of a compact pump/air separator of the subject invention;

FIG. 3 illustrates a partial sectional view taken along line 3--3 of FIG. 2;

FIG. 4 illustrates a sectional view taken through the inlet and filter assembly of the subject compact pump/air separator;

FIG. 5 illustrates a partial sectional view taken along line 5--5 of FIG. 2;

FIG. 6 illustrates a sectional view taken along the control valve of the subject compact pump/air separator; and

FIG. 7 illustrates a sectional view taken along the by-pass valve of the subject compact pump/air separator.

DESCRIPTION OF THE PREFERRED EMBODIMENT

A schematic illustration of the compact pump/air separator of the subject invention is shown in FIG. 1. The compact pump/air separator is designated by the numeral 1 and is connected to an underground gasoline storage tank 2 via suction piping 3. The compact pump/air separator 1 comprises a pump 4 of the constant delivery type which is directly connected to the suction piping 3 at its inlet suction end, and is connected at its outlet or pressure end to an air separator 5. All of the flow from the constant delivery pump is directed through the air separator 5 and the air separator 5 functions to separate pure gasoline (i.e., without air and vapor) from a scavenged flow consisting of a small percentage of the liquid gasoline flowing from the pump 4 and the air and vapor in the flow. The pure gasoline is conducted from the air separator and is passed either through a control valve 6 and out of the compact pump/air separator to the delivery hose for dispensing or, alternatively, through a by-pass valve 7 and back to the inlet or suction side of the pump 4. The scavenged flow from the air separator is conducted to a cavity or atmospheric chamber 8 in the compact pump/air separator unit. Cavity 8 is provided with conditions conducive to static air-separation effects, i.e., the tendency of air to rise and separate from liquid by gravity. The air is permitted to vent to the atmosphere, while the remainder of the scavenged flow consisting of pure gasoline is collected in the cavity and is conducted through a suitable orifice controlled by a valve 9, preferably of the float valve type, and back to the inlet or suction side of the constant delivery pump 4.

The arrangement of elements in the subject pump/air separator provides the desired compactness for use in gasoline dispensing apparatus and, in addition, provides an arrangement whereby the by-pass is located downstream of the air separator. Heretofore, it has been the common practice to mount the by-pass valve in the single conduit extending between the pump and air separator. In that the pressure in the lines between the gasoline storage tank and the pump is below atmospheric pressure, opening of the by-pass line often caused the accumulation of air in the system causing the pump to become airbound. Hence, with the dispenser nozzle fully closed and all of the flow being recycled through the by-pass valve, the air introduced into the by-pass line would accumulate in the by-pass line and pump, thereby affecting the efficiency of the pump. With the compact pump/air separator of the subject invention, as illustrated in FIG. 1, this condition is obviated by placing the by-pass valve downstream of the separator whereby only pure gasoline is passed through the by-pass line. Other advantages of this system will become apparent as the preferred embodiment of the subject compact pump/air separator is described with reference to FIGS. 2 thru 7.

Turning to FIGS. 2 and 3, a compact pump/air separator of the subject invention comprises a housing 20 including three internal cavities A, B, and C which are interconnected, as more fully described below. Housing 20 also includes an inlet, designated by numeral 21 and two outlets: (1) an air venting outlet 22 in communication with cavity C; and (2) a controlled outlet 23 disposed in cavity B.

Referring to FIG. 4, the inlet 21 of the housing 20 is in communication with cavity A that includes an enlarged entrance section A' to accomodate a filter F. Filter F is located immediately inside the housing and functions to prevent the ingestion of foreign particles into the compact pump/air separator. The piping 3 which is in communication with the inlet 21 extends to the underground gasoline storage tank (see FIG. 1).

Cavity A is generally U-shaped in cross-section with a constant delivery pump 30, preferably of the vane type, being located in one leg portion of cavity A. Pump 30 is driven in conventional manner through a shaft 31 which is suitably mounted in housing 20, and is connected to drive wheel 32 (see FIG. 3) located externally of the housing. The motor (not shown) for driving wheel 32 is located in the gasoline pedestal (not shown), as is the compact pump/air separator of the subject invention.

The other leg of the U-shaped cavity A is generally annular in cross-section and forms a portion of an air separator, designated by numeral 40. Located along the longitudinal axis of the separator is a tubular scavenging tube 41 which is cantilevered from an internal wall 42 of the housing. A restricted orifice 43 is provided through wall 42 along the centerline of the scavenging tube 41 thereby interconnecting cavity A to cavity C.

The air separator 40, and hence cavity A, is also in communication with cavity B at a location downstream of the entrance 41a to the scavenging tube. As shown in FIGS. 2 and 5, the transitional opening between cavities A and B is preferably equal to the cross-section of said cavities whereby no restriction of the flow from cavity A to cavity B is effected. FIG. 5 also illustrates the position of the scavenging tube relative to transition region between cavities A and B. As illustrated, the cross-section of the internal walls of the housing 20 defining the air separator 40 is generally annular so as to promote centrifugal or helical flow of the pressurized gasoline leaving the pump 30, as more fully described hereinafter.

A detailed sectional view of controlled outlet 23 is illustrated in FIG. 6. Controlled outlet 23 comprises an aperture 50 which is tapered as at 51 to cooperate with the slidably mounted seat 53 of valve 52. The seat 53 of valve 52 is biased in the closed position by spring 54. The body of valve 52 includes a contoured diffusor 55 which connects to tubing 56. The latter extends to the metering device of the gasoline dispensing apparatus (not shown). As illustrated in FIG. 6, the controlled outlet 23 is in the fully opened position whereby pure gasoline passes from the cavity B to the metering device and thence through a flexible hose and a dispensing nozzle at the delivery end of the hose. It is noted that the spring 54 forces the valve 52 to the closed position when the pump is inoperative, thereby preventing the back-flow of gasoline from the dispensing hose to the cavity B.

A second outlet from the cavity B comprises a by-pass outlet 24 that extends through an internal wall 44 of the housing 20 interconnecting cavity B with cavity A in the region of the suction side of pump 20. A detailed sectional view of the by-pass valve arrangement is illustrated in FIG. 7, and comprises a slidably mounted seat valve 60 which is biased toward its closed position by spring 61.

Referring to FIG. 3, cavity C includes a second outlet in a form of a tapered orifice 70 consisting of two tapers 70a and 70b interconnecting cavity C to cavity A, in the region of the suction side of pump 30. Orifice 70 is disposed at the lowermost portion of cavity C and specifically in the region where the pure gasoline of the scavenged flow collects. Disposed in the cavity C is a float 71 having at its lower end a spherical seat valve 72 and a throttle pin 73, both of which cooperate with said orifice 70 to perform separate functions during the operating cycle of the pump as will be described later in detail. The float valve 71 is confined to translationable movement by: (1) cooperation of the valve stem 74 with an internal annular wall 45 of the housing 20; and (2) a guide mechanism 75 which is suitably connected to the upper end of the float valve.

The general operation of the compact pump/air separator will now be described. Upon the service station operator removing the nozzle dispenser from the pedestal and actuating the pump switch, pump 30 will begin to rotate thereby creating a suction force for lifting gasoline from the storage tank 2 and through piping 3. Gasoline, which includes air and vapor, enters the compact pump/air separator through inlet 21, passing through the filter F and into cavity A adjacent the suction side of pump 30. The pressure at this point is usually 10-12 inches of mercury below atmospheric because the gasoline must be lifted from an underground storage tank. The gasoline then enters the vane pump 30 and is discharged under pressure into the air separator 40. As the gasoline enters the air separator portion of cavity A, the internal construction of cavity A causes the gasoline to assume a helical flow path or swirling motion. The gasoline enters the air separator with a velocity which can be regarded as consisting of two components, namely, Va which is the axial component, and Vt which is the tangential component.

The average axial velocity and the actual velocity can be calculated by the following equations:

The helix angle is the angle between the tangential velocity and actual velocity of the gasoline. The helix angle θ at the entrance to the separator can be determined by the following relationship:

θ = sin -1 (Va/V)

It has been determined that the air separate operates at maximum efficiency through only a narrow range of helix angles. If the helix angle is too small, considerable power is consumed in accelerating the gasoline, whereas if the helix angle is too large, separation of the air and vapor from the gasoline is not completely effected. It is also noted that the input to the air separator may be either tangential or axial, as long as the proper swirl or helical path is induced to the gasoline flow. As mentioned above, the helix angle is a very important parameter for the efficient operation of the air separator, and it has been found that the subject separator operates satisfactorily with a helix angle in the range of 10° to 30°. It has also been found that the separator operates best with an axial velocity (Va) of 3 to 6 ft./sec. The prior art considered it essential that the axial velocity be held as low as possible in order to promote gravity separation. The actual velocities were probably no greater than 0.3 to 0.6 ft./sec., thus resulting in a separator chamber which is 10 times greater in cross-sectional area than the device of the present invention.

Returning to the operation of the subject pump/air separator, air bubbles and vapor in the gasoline flow will be forced into the center of the air separator by the action of centrifugal force caused by the swirling gasoline, and will form a central core in the flow. This core is collected in the scavenging tube 41 and allowed to exit the air separator through the orifice 43 and into the cavity C, along a small percentage of gasoline. It has been found that 3 to 8 percent of the total pressurized gasoline leaving the pump 30 is sufficient to separate substantially all of the air bubbles and vapor from the main gasoline flow when the bubbles constitute less than 12 percent of the main flow by volume. Increasing the size of orifice 43 to permit 8 percent of the pressurized gasoline flow to leave the separator through the scavenging tube 41 effectively expands the separating range to 18 percent air bubbles and vapor from the main gasoline flow.

The air and scavenging gasoline flow enter the atmospheric cavity C where the air is vented to the atmosphere through air outlet 22. When sufficient pure gasoline collects in the cavity C, the float valve 71 is actuated whereby the gasoline collected in the lowermost portion of cavity C is returned to cavity A in the region of the suction side of the pump through the orifice 73.

The main flow of gasoline, now devoid of air bubbles and vapor continues past the scavenging tube 41 and flows from cavity A to cavity B. Pure gasoline leaves cavity B either through the control valve 23 if delivery is occuring, or through the by-pass valve 24 into cavity A if the pump flow exceeds the delivery out of the meter and dispensing nozzle.

The arrangement of the subject pump/air separator permits the full pump flow which is relatively constant to pass through the air separator, while maintaining the swirl conditions which produce the efficient separation of air and vapor from the pressurized gasoline. At the same time, the arrangement of elements of the subject pump/air separator prevents an accumulation of air on the suction side of the pump during a condition of full by-passing of gasoline from the cavity B to the cavity A.

It is noted that the control valve 23 is designed so that in the event suction is taken on an empty gasoline storage tank whereby the pump discharges only air, sufficient back pressure is provided by the spring 54 (see FIG. 6) to force all the air through the scavenging orifice 43. Accordingly, this arrangement maintains only pure liquid gasoline in the meter, flexible hose, and dispensing nozzle, and insures accurate product measurement by the metering device of the gasoline dispensing apparatus.

Orifice 43 achieves a second function in addition to its function in conjunction with the air separator scavenging tube 41. The second function is to discharge all the air delivered by the pump in the event the storage tank 2 becomes empty while a delivery is being made through the dispensing nozzle of the gasoline pump unit. Assuming that the compact pump/air separator is capable of accommodating 8 percent of 15 gallons per minute of fluid gasoline flow, or in other words, 1 gallon per minute of gasoline will pass through the scavenging orifice with a 15 p.s.i. pressure difference. In the empty storage tank condition, 15 gallons per minute of air would be required to pass through the same orifice. In order to calculate the pressure differential necessary to accomplish this situation, it is noted that the flow through an orifice is proportional to the square root of the pressure difference. This relationship may be expressed as follows: (1)

Qair = C√ ΔP where C is a constant of proportionality.

Since air passes through an orifice 25 times more readily than liquid gasoline, it is recognized that 25 gallons per minute of air will pass through the orifice 43 with a 15 p.s.i. pressure differential. Setting these values into equation (1) and solving for the constant C results in a determination that the pressure differential is 5.4 p.s.i.. Accordingly, using the parameter of a 5.4 p.s.i. pressure differential, it is a relatively simple matter to design the control valve 23 to maintain this designated differential or back pressure on the scavenging orifice 43. Hence, a flow of 8 percent through the scavenging orifice not only provides for efficient air separator operation, but also provides the capability of meeting the "empty tank condition," which is required in retail gas dispensers, in a very simple manner.

The control valve 23 functions to maintain liquid gasoline in the meter and the delivery hose when the pump is not in operation, and to provide a back pressure in the cavity C in the event the gasoline storage tank is emptied during a delivery of gasoline; it being noted that either of these conditions would force air through the meter which would be recorded as product delivery. During a normal delivery operation, the control valve has no function other than to allow the flow of gasoline from the cavity B to the metering device. It should therefore be designed to provide a minimum pressure drop when gasoline is being delivered to the meter. This is accomplished by providing an unloading disc 53a which is closely fitted to the valve body except in the area of the opening to the diffusor 55 (see FIG. 6). In this position, the force of spring 54 is balanced by forces acting on the control valve 23 which arise from two sources. The first is the momentum of the fluid entering the valve 23 through aperture 50. In accordance with the principles of momentum, a force is required whenever a fluid stream changes direction. The components are so arranged that this force is supplied by the valve 52 and tends to aid in compressing spring 54. The second force is the pressure differential across the unloading disc 53a. The aperture 55a of diffusor 55 is the smallest area the fluid stream will encounter in the valve 23, consequently it will be the highest velocity and lowest pressure. The rear side of the disc 53a is vented to this low pressure area at the aperture 55a. The area which this pressure difference acts upon is the entire area of the unloading disc 53a which is approximately eight times greater than the area of the seat 53. Since the spring 54 must be designed to provide at least a 5.4 p.s.i. differential, pressure across the seat in the closed position, in theory, one eighth of this differential pressure acting on the greater area of the disc 53a, i.e., 0.6 p.s.i. would be sufficient to compress the spring 54 to the open position. In practice it has been found that due to losses approximately one fourth of the pressure drop required to open the valve, i.e., 1.2 p.s.i. is required to maintain valve 23 in the open position.

The control valve 23 also provides for a reverse flow relief valve to limit the pressure of the liquid gasoline maintained in the meter and hose by the control valve 23. The volume of gasoline trapped between the control valve and the nozzle at the end of the hoze when heated will increase and cause an increase of pressure of the gasoline between the control valve 23 and hoze nozzle valve. To keep the liquid pressure within safe limits, a relief valve is provided to maintain the pressure at some reasonable value slightly above the maximum pump pressure. The liquid is relieved through the air separator 5 of FIG. 1 to the atmospheric chamber 8. This added liquid is returned to the pump through float valve 9 on the next delivery cycle.

The float valve (element 9 of FIG. 1 and element 71 of FIG. 3) must also perform two functions. At startup of the compact pump/air separator, the pump must operate to draw gasoline from the storage tank which may require a lift of approximately 20 feet. Even a small leak in the compact pump/air separator will admit air to the suction side of the pump and destroy the suction vacuum which is required to lift the gasoline from the storage tank. The spherical seat of valve 72 provides for complete sealing of the float valve 71 when no gasoline is present in cavity C.

The second requirement of the float valve 71 is to regulate the gasoline level in cavity C by providing a throttling action which is controlled by the position of the float. The operation of the float valve is as follows: At startup, the float valve will be in a closed position whether or not gasoline is present in cavity C. As gasoline enters the atmospheric chamber C through the scavenging orifice, the gasoline level will rise until the buoyancy forces of the float are sufficient to overcome the weight and the pressure forces acting on the spherical seat 72 of float valve 71. At this point the float valve will rise and the pressure forces will act only on the end of the pin 73 which is a much smaller area than the spherical seat. This will cause the float to rise to the limit of its motion. The movement of the float valve is restrained so that the pin 73 will be positioned near the top of the tapered orifice 70b and a considerable area will be available for flow from the atmospheric cavity C causing the gasoline level to fall. However, the pressure forces will continue to act on the end of the pin 73. To achieve this it is important that the pin 73 be positioned at or slightly below the top of tapered orifice 70b and that the annular area remaining between the pin and the taper be slightly less than the area across the smaller end of the tapered orifice 70b. When the buoyancy forces are equal to the weight and pressure forces, the pin 73 will move downward with the gasoline level. As the pin 73 moves downward, the area exposed to the pressure forces remains constant, therefore no new forces are introduced. The area available for flow from the atmospheric cavity C decreases as the pin 73 moves downward into taper 70b which decreases the flow from the cavity C. When the flow entering and leaving the cavity C are the same, the liquid level will remain constant.

In summary, the compact pump/air separator of the subject invention provides the desirable characteristics of compactness, efficiency in removing air and vapor from gasoline, and an arrangement of elements which prevents the recycling of air and vapor to the suction side of the pumping unit. Also where a centrifugal pump is employed the device can function to separate lighter density particulate matter from a heavier density fluid or to separate the lighter density fluid from a heavier density fluid which is immiscible with the lighter density fluid.

Although a specific embodiment of the subject pump/air separator has been described hereinabove and illustrated in the drawings it will be understood that other constructions of the subject pump/air separator readily apparent to those skilled in the art are contemplated to be within the scope of this invention.